FIG. 57 shows an incubator 9 conventionally used for cultivating various microorganisms or cells. The incubator 9 comprises a chamber 91 having an opening 90 closable with a door 92 and a plurality of racks 93 arranged in the interior of the chamber, and is adapted to place a plurality of microplates 31 on the respective racks 93. The chamber 91 is provided with an environment adjusting device (not shown) for adjusting the ambient conditions inside the chamber 91, such as temperature, humidity, carbon dioxide concentration, etc. Samples on the microplates 31 are cultivated under suitable ambient conditions set by the device.
To check the state of samples being cultivated in the incubator 9, the microplate 31 is withdrawn from the chamber 91, and the samples are observed or analyzed using, for example, a microscope. Since the door 92 of the chamber 91 must be opened at such a time, there is the problem that the interior ambient conditions of the chamber 91 are greatly altered by opening the chamber.
Accordingly, an incubator has been proposed in which the microplate is made transportable between a microplate inlet formed in the chamber and a microplate accommodating portion within the chamber so that the microplate can be moved into or out of the accommodating portion automatically (see, for example, the publication of JP-A No. 1999-89559). Because the proposed incubator can be thus adapted by forming a small microplate inlet in the chamber, the internal ambient conditions of the chamber will not be altered greatly by moving the microplate into or out of the chamber.
With the incubator described above, however, the chamber is provided inside thereof with a microplate transport mechanism and also the microplate racks, and nearly half of the interior space of the chamber is occupied by the transport mechanism. This entails the problem of reducing the number of microplates that can be accommodated in the chamber.
The incubator is provided with an environment adjusting device for supplying a gas for adjusting the environment. In order to diffuse the gas into all the microplate accommodating portions having the microplate racks, a gas discharge outlet is provided as directed toward the outside of the space wherein the racks are installed, i.e., toward a space wherein the microplate transport mechanism is disposed. Thus, the gas discharge outlet is positioned at one side of the interior of the chamber, consequently producing a markedly uneven flow of gas inside the chamber and giving rise to the problem that the ambient conditions differ from position to position within the chamber.
Further with the incubator described, the device for transporting the microplate inside the chamber has a motor disposed outside the chamber and provided with an output shaft which extends through the wall of the chamber and is coupled to the mechanism inside the chamber. Accordingly, for the maintenance of the transport device, it is necessary to remove the motor from the chamber and to disassemble the main body of the transport device within the chamber to some extent, hence the problem of necessitating a cumbersome procedure. The motor output shaft extending through the chamber wall further requires provision of a sliding bearing which is highly airtight. This results in the problem of making the chamber complex in construction.
The microplate racks inside the chamber are arranged with a predetermined pitch, so that the incubator described is provided with a microplate transport control program which is specific to the construction of the racks. Accordingly, if it is attempted to install microplate racks of different structure in order to accommodate microplates having a thickness larger than the predetermined pitch, there arises the problem the control program must be rewritten.
Further when a microplate is to be placed into the chamber anew, the operator must specify the position where the microplate is to be placed and needs to input microplate identifying information for the management of the microplate within the chamber. The incubator described therefore has the problem that the operator must perform a very cumbersome manipulation procedure.